Employee Benefits - Schedule of Components of Our Company-Sponsored Pension Plan Costs (Details) - Qualified and Nonqualified - Defined Benefit Pension Plans - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 5.9	$ 7.7
Expected return on plan assets	8.5	12.0
Amortization of prior net losses	2.2	3.0
Amortization of prior net service credit	(0.1)	(0.1)
Total net periodic pension expense (benefit)	$ (0.5)	$ (1.4)